STRESSED and nervous? Try keeping a bowl of lemons and oranges on your desk. Feel claustrophobic? Sniff some cucumber. Want to lose a few pounds? Inhale the fragrance of green apples.

Tests on lemons have found that the scent could reduce levels of stress []

People have used the scents of plants, trees, herbs and fruits since ancient times to fight inflammation, depression and induce sleep. “Smells act on the brain like a drug,” says neurologist Dr Alan Hirsch, founder of the Smell and Taste Treatment and Research Foundation in Chicago.

“In the future there will be new treatments based on smell.”

Smells stimulate nerves in the nose that send impulses to the brain. These impulses usually go to the brain’s limbic system which controls heart rate, blood pressure, breathing, memory, stress levels and hormone balance.

Professor Hanns Hatt from Ruhr University Bochum, Germany, says his experiments with jasmine “can be seen as evidence for the scientific basis of aromatherapy”, a form of alternative medicine using the pure essence of a plant as an essential oil.

Yet some effects of scent are psychological. For instance, certain smells are therapeutic because we associate them with pleasant memories. One whiff of menthol rub may make people with a chesty cold feel better because it reminds them of being nursed by a doting parent as a child.

Feel better with a whiff of your favourite fruit or flower

LAVENDER

Lavender pillows may help you sleep. Dr Mark Moss of Newcastle’s Northumbria University found that lavender has a consistent sedative effect. It slows reactions, reduces attention and impairs working memory, the part of the brain that puts facts on hold before storing them.

Lavender may also help the elderly avoid falls and be less agitated. Researchers at the Department of Internal Medicine and Rehabilitation Science at Tohoku University recently did three trials on lavender in randomly selected nursing homes in northern Japan. Some residents wore a lavender skin patch while others had unscented patches.

Those who smelled the lavender had significantly fewer falls and were calmer. Researchers speculate that lavender has a stabilising effect on balance.

JASMINE

The sweet white flowers could be nature’s Valium.

Researchers at Ruhr University led by Prof Hatt found that brains can respond as well to jasmine as to sedatives and barbiturates.

In an experiment last year the performance of Chicago White Sox baseball players improved when they wore wristbands saturated with jasmine. Independent assessors judged the batters by the mechanics of their swings, including bat speed, trajectory and the flight of the ball.

ROSEMARY

A rosemary plant on your desk could improve your work performance and how you feel about it. The old saying “rosemary is for remembrance” seems true. Smelling the herb produces beta brain waves which demonstrate alertness.

The link between smelling rosemary and scoring higher on mental tests was established by Dr Moss in 2003. However, more surprising news was to come.

Dr Moss has now demonstrated that after inhalation of the herb one of its main compounds, 1.8-cineole, could be detected in the bloodstream. The more of the compound in the bloodstream the more cognitive performance was improved.

Dr Moss believes the aroma which entered the bloodstream via the nasal membranes and lungs acts like a traditional drug. If it can work when ingested maybe one day we could have a pill to keep us mentally alert into old age.

APPLE

Sniffing green apples may control blood pressure, lessen migraine pain and help you lose weight.

Dr Gary E Schwartz, professor of psychology, medicine, neurology, psychiatry and surgery at the University of Arizona, found that in particular the smell of spiced apples can control blood pressure as well as meditation.

In studies of healthy volunteers under stress it has brought systolic blood pressure, the peak pressure during heart beats, down by an average of three to five points and sometimes lowered diastolic blood pressure, the resting pressure in between beats.

Apples may also reduce migraine pain. In the knowledge that research suggested some smells can trigger migraine Dr Hirsch theorised the opposite could also be true. He investigated the effects of green apples since previous studies had pointed to their ability to reduce anxiety. Many patients had less pain but only if they liked the smell.

Dr Hirsch also found that the smell of apples might curb appetite. He asked 3,193 overweight people, mostly women aged 18 to 64, to smell green apples and other sweet smells including banana and vanilla when they were hungry. After six months they lost an average of 5lb a month and 30lb in total.

LEMON

Several studies demonstrate that the smell of lemons can reduce stress at least in rodents.

In one investigation the technical research centre at the Japanese flavour and fragrance company T Hasegawa gave stressed lab rats linalool, a component of lemons.

The linalool returned their stress-elevated levels of neutrophils and lymphocytes, key parts of the immune system, to near-normal levels. It also reduced the activity of more than 100 genes that go into overdrive during stress.

The researchers say their findings could form the basis of new blood tests for identifying stress-busting fragrances. At the Institute of Pharmacology in Tübingen, Germany, mice that became active after exposure to oils of rosemary and dwarf pine calmed down with oils of lemon balm and valerian.

PEPPERMINT

Getting pumped up with peppermint may improve workouts and accuracy in the workplace.

Dr Bryan Raudenbush at Wheeling Jesuit University, West Virginia, found that athletes who sniffed peppermint during exercise ran faster, had greater grip strength and could do more push-ups than those who did not.

He also found smelling peppermint improves clerical work, including typing accuracy and speeds and may make drivers more alert. He says peppermint and cinnamon both fight driving fatigue.

ORANGE

In 2000 researchers at the University of Vienna’s Neurological Clinic examined the response to orange scent in a dentist’s waiting room. The odour had a relaxing effect, mostly on women. Compared to patients not exposed to the scent they had lower anxiety, felt more positive and were calmer.

Violent criminals in Rotterdam in the Netherlands became less aggressive and had fewer fights when exposed to the scent of oranges, according to a 2008 study.

During the four-week experiment inmates were calmer and needed fewer sedatives when orange smells were circulated through prison cell air vents.

CUCUMBER

In one of Dr Hirsch’s experiments three quarters of claustrophobic volunteers felt better about being in a lift after smelling cucumber.

Some hospitals apply cucumber oil on a cotton square and put it under a patient’s nose while they have MRI scans.

Dr Hirsch speculates that there is something in cucumber that changes people’s perceptions of space.